Modern gas turbine engines, such as the General Electric CFM56-5B and -7B with dual annular combustor engines, have been designed to operate both efficiently and with low amounts of pollution emissions. The engines typically include lubrication systems in which lubricating oil is carried externally of the engine in a separate tank or reservoir. In some modern gas turbine engines, the bearing assemblies are lubricated with oil, and heat from the engine parts is absorbed and dissipated by the same oil. It is known to house the engine bearing assemblies in their own respective sumps. The major components of a dry sump lubrication system include a lubricating oil reservoir or tank, a supply pump for supplying lubricating oil from the reservoir to the bearing assembly sumps under pressure and a scavenge pump for removing lubricating oil from the bearing assembly sumps. The scavenge pump causes the return lubrication oil to pass through a heat exchange assembly, on its way to the tank or reservoir. The heat exchange assembly often puts the return lubrication oil in heat exchange with the jet fuel used by the engine. Fuel, on its way to the combustor, enters and passes through the heat exchanger at a much greater flow rate than the oil, so that large quantities of heat are absorbed from the oil by the fuel. Appropriate filter means are also included in the system to remove contaminants from the oil.
The system also includes the necessary lubrication and scavenge tubes. The lubrication and scavenge tubes are often secured to the engine cases, frames, ducts, etc. by clamps and brackets. These lubrication and scavenge tubes run from the pumps to the turbine rear frame.
A problem sometimes encountered is heavy coking and blocking of the oil scavenge tubes on the turbine rear frame. This problem may be addressed by stripping the turbine rear frame, including the scavenge tube, off of the low pressure turbine module for cleaning, as the scavenge tube cannot be remove or flushed in situ. During this cleaning, the turbine rear frame may be positioned horizontally and the scavenge tube then blocked at one end. Cleaning fluid may then be manually poured into the tube and after an appropriate amount of time the fluid may be eliminated from the tube. This process may be repeated for several hours, even days, until the tube is cleared of the blockage. Although this cleaning process may be effective, it is often costly and time consuming.
Accordingly, there exists a need for effective cleaning processes for cleaning tubes, cavities or similar bodies. There is also a particular need for a process and apparatus for cleaning oil scavenge tubes of gas turbine engine components, particularly oil scavenge tubes of a turbine rear frame. The present invention satisfies these needs.